Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

The use of nitrous oxide, or laughing gas, during childbirth fell out of favor in the United States decades ago, and just two hospitals — one in San Francisco and one in Seattle — still offer it. But interest in returning the dentist office staple to the delivery room is growing: respected hospitals including Dartmouth-Hitchcock Medical Center plan to start offering it, the federal government is reviewing it, and after a long hiatus, the equipment needed to administer it is expected to hit the market soon.

Lori Rowell, due to give birth to her second child in June, is intrigued by the option.

"I would definitely think about it, and read about and talk to my doctor about it," said Rowell, 36, of Concord. "It is nice to know that it doesn't affect the baby, because that's what scares me about an epidural."

Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

Though nitrous oxide is commonly used for labor pain relief in Canada, Great Britain and other countries, it's been all but abandoned in the United States in favor of other options, such as epidurals, said Judith Bishop a certified nurse midwife at the University of California San Francisco Medical Center and leader in the effort to reintroduce nitrous oxide for labor.

With an epidural, medication to block pain seeps through a tube into space surrounding the spinal cord. Because it must be administered by an anesthesiologist, an epidural is significantly more expensive than nitrous oxide. Both are covered by insurance.

"In this country, most people when they hear about nitrous, they think it sounds pretty retro, that it sounds very old-fashioned and they're sure there's something bad or dangerous about it and we must've chosen to eliminate it. But I think we eliminated it because we went for the more specialized, higher-tech options," said Bishop, who will be among the speakers Monday at a conference for New Hampshire, Vermont and Maine hospital officials.

She and other advocates of reintroducing nitrous oxide emphasize that it is no silver bullet — it "takes the edge off" pain rather than eliminates it. But they say it should be among the options offered to women, particularly those who give birth at small or rural hospitals that lack round-the-clock anesthesiologists. Laughing gas is easy for women to self-administer, takes effect quickly, and can be used late in labor.

"It's not right for everybody, but it's something that for many women will offer a certain amount of relief," Bishop said.

Michelle Collins, a certified nurse midwife and assistant nursing professor in Tennessee, previously worked as a nurse in London and saw how widely and well nitrous oxide was used there. She has been working with an anesthesiologist to bring nitrous oxide for laboring women at Vanderbilt University Medical Center and said she expects it to become available later this year.

Early Wednesday morning, she delivered a baby to a woman she said would have been a perfect candidate for nitrous oxide: the mother arrived at the hospital at midnight and gave birth about three hours later.

"There was a period of time just before birth when she was starting to lose it. Nitrous would've been awesome for her: just a few puffs to get her over that hump," she said.

Vanderbilt has purchased second-hand equipment to deliver nitrous oxide, but Dartmouth-Hitchcock and others are hoping to buy new equipment that is expected to become available in April. After obstetric demand for nitrous oxide dropped, the one company that made the equipment stopped. But a new company has stepped into that gap and has begun taking orders.

At Dartmouth-Hitchcock, where officials plan to order two machines, nurse midwife Suzanne Serat estimated that 10-20 percent of her patients might try nitrous oxide.

"We have a number of people who don't want to feel the pain of labor, and nitrous oxide would not be a good option for them. They really need an epidural, and that's perfect for them," she said. "Then we have a number of people who are going to wait and see what happens, and when they're in labor, decide they'd like something and then the only option for them is an epidural but they don't need something that strong. So they would choose to use something in the middle, but we just don't have anything in the middle."

The hospital hopes to begin offering nitrous oxide for labor by summer. In the meantime, the federal Agency for Healthcare Research and Quality is reviewing the effectiveness and safety of nitrous oxide compared to other pain relief methods.

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